Power tube



Sept.l 11, 1934. E. MoURoMTsEFFl-rr A1. 1,973,094

POWER TUBE Filed April 27, 1929 4 sheets-sheet 1 /z'g l fige.

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` ATTORNEY SePt 11 1934- l. E. MoURoMTsEFF Er AL 1,973.094

POWER TUBE Filed April 27, 1929 4 Sheets-Sheet 2 and Gregaryfglffy POWER TUBE 4 Sheets-Shea?l 3 Filed April 27, 1929 A'TTORNEY Septll, 1934.l E, MOUROMTSEFF Er Al. 1,973,094

POWER TUBE Filed April 27, 1929 4 sheets-Sheet 4 |NVENTORS I /l'a E Maur-om aeff and Gregory l/E 9A/y.

Patented Sept. 1l, 1934 Unire' vstares POWER TUBE Y I A Ilia E. Mouromtsei and Gregory V. Rylsky, Wilkinsburg, Pa.,v assignors to Westinghouse Electric and Manufacturing Company, `a corporation of Pennsylvania .Application aprill 27, 1929, serial.rifzwaeoe.

l 1o claims. (creto-2755 "Our invention relates to electron-discharge tubeshaving control electrodes, and particularly to electron-.discharge tubes designed for generat- 7 ing .large amdunts of power or for generating very high-frequency currents.

Importer `tubes of conventional design, difficulty has been encountered because of the control electrode or gridbecoming heated to such kan extent, during theioperation of the tube, that elec- '10 trons are emitted therefrom. The greater the amount oi the power generated and the higher the frequency .Oi the current, the greater is the diculty encountered.

An object of our invention is to prevent vthe emission of electrons from the control electrode in an electron-discharge tube -of the above-mentioned type by cooling the control electrode.

A further object of our invention is to provide a structure that will permit cooling of both the f2() control electrode and the anode and which, at the same time, is simpleA in construction and .of ;the necessary mechanical strength.

lIn practicing our invention, we employ an eyac- Hated vessel having a m-etal wall which constitutes the anode, a metal tube positioned within the metal wall, a plurality of filaments supported within the vessel to `constitute the cathode, and a plurality of discs mounted on the metal tube. The discs yhave openings around their peripheries, and the laments are so supported that they extend through these openings. The discs, together with the metal tube, constitute the control electrode or grid. The grid is cooled by circulating water or air through the metal tube, as is more fullydescribed hereinafter.

' Other features and advantages of our invention will appear from the following description, taken in connection with the accompanying drawings in which:

Figure 1 is a View, in longitudinal section, of a power tube constructed in accordance with one form of our invention; I

Fig. 2 is a View, in longitudinal section, of a power tube constructed in accordance with a niodication of our invention;

Fig. 3 is a View, in lateral section, taken on the line Il-III ci Fig. l;

Fig. 4 is a View, in lateral section, taken on the line `IV-IV of Fig. 2; y

Fig. 5 is a View, in lateral section, of a modication of the grid structure which may be employed in any of the power tubes illustrated;

Fig. 6 is a view, in lateral section, of a further modication of the grid structure which,

also, may be employed in any of the'power tubes illustrated.

Fig. 7 is a View, in lateral section, taken on the line VII- VII ,of Fig. 7a.rof a still further modification of the grid structure which may be employed in any of the power tubes illustrated.

Fig. '7a is a View, in longitudinal section, takenk on the line VIIe-,Vila of` Fig."7. Fig. 8 is a View; in longitudinal section,'of the upper part of a power tube constructed-inaccordance with a further modification of our invention; 565

Fig. Sais a detail view of part of the structure shown in Figp8. '7 f I v Fig. 9 is a View, in longitudinal section, ofthe lower part ofthe above-mentioned power tube; l

Fig. l0 is Vaview,V in lateral'section; taken on 70 thelineX--Xoflig8; v`

'Fig 1l is a View, in lateral section, taken on the line VXI-Xl of Fig. 9; fandVV i Y Fig. v12 is a View, in lateral section,- talienon the une XII- XII of Fig. 9.Y '75 Referring tovFigsQl and 3 of the drawings', the

apparatus comprises anevacuated vessel formed by an outer'metal tube l which acts as the anode and which is closed at the upper end by a metall n piece integral withthe tube. The lower end ofl the tube is closed by means of' a glassmemberZ which is sealed to it and byimeansl o f a'rnetallio re-entrantportion 3 sealedV to a re-entrant portion v of the glass member 2 at a seal 4 The metallic reentrant portion v3 forms partof` 85 the grid of the power tubej andis inthe formpf a metal tube 5 closed at the upper end bymeans Vof a metal'piece integral with it.l A pipe 6y is positioned within, and` spaced Afromfthe tuber j By means of this structure, the grid may be cooled by forcing water or some other cogling fluidinto the reentrant portion 3 between the tube Band the pipe' 6 and out through the pipe ,6; l

Thereentrant metalportion 3 alone may act as a control electrode if a very lo-W amplification -95 factor does not interfere with the tube performance; otherwise, metal pieces are so mounted thereon that they projectto points 'in'proximity to the laments, as in the construction shownfn Figs. 1 and 3 and as in the modied construction V'100 shown in'Figs'. 2 'and/i to'and- '7a.

`n the structure illustrated in Fig. 1,'thecont'rol Yelectrode comprises a plurality of'metaLdiscs 7 (only the end discs are shown) mounted on the reentrant portion 3 and spacedapart by washers` -/105 8.]The discs'l are heldin-po'sitionbyl collars 9 fastened to the relentrant tube jbymeans of set screws. Holes 10 are locatedn'ear the peripheries of the discs '7, as shown in Fig. 3,k and the discs are so positioned that the holes are alignmentl'llb' Since the filaments l 1l are so "supportedfthat they extend through the holes 10,'part of `the grid is pcsitionedbetween theiilaments-and the anode,

Vwhile 'another party ofthe grid is lpo'sitior'iied on the sideof the filaments Yremote frorfnvtheanodez As previously vpointed out,however,` it i's not essen'- tial that the control'electrode shall extend completely around Athe filaments.'V .L I The upper ends of the filaments i171 are supported and electrically connected by means `offrods l- 11al secured to a metal ring 12. The supporting structure for the ring 12 comprisesv a rod 13 of insulating material, such as quartz, that is clamped in a split supporting member 14 .which is welded or otherwise attached, in any suitable manner, to the upper end of the reentrant poi'- tion 3. The ring 12 is attached to the upper end of the rod l3by means of another split supporting member l5 which is attached `to the ring 12 and clamped to the rod I3.

The lower end of the filaments 11 are attached to rods 11b supported by means of rings 16 which are bolted to terminal rods sealed in thereentrant portions 2a of the glass member 2.y In practice, several filaments would be supported by each of the rings k16 instead of .the single .iilament Vwhich appears in the lsectional view Inthemodificationof the 'grid structure shown ,inFig. 5, portions'o'f thegriddiscs 7 are cut away to improve Ythe characteristics ofthe power tube without decreasing the control effect of the grid. Also, Ysix` filaments instead of two are utilized, although, obviously, a larger or smaller number of filaments may be utilized if desired.

In the modification ofthe grid structure shown in'Fig. V6,`sectionsof the grid discs 7 have been.

cut away so that the grid comprises the reentrant Atube'together witha plurality of pieces 17 which l do not completely encircle thefilamentsll. Ob= viously, the projecting piecesY 17 may assume Various forms, other than the exact form shown. While six filaments have been illustrated in this modication, .it is obvious that the number of laments may be increased .or decreased as de- .from. lSections of the'ribs 19 maybe so cut away,

as indicated'in Fig.V 7d, that the ribs assume the f form of rowsof rod-like projections. .The tube 18 is employed, the grid may be assembled much moreconveniently than when the disc structure Lshown in.Fi'g. 1 is employed. By cutting away portions ofthe ribs to form rod-like projections,

. as described above,.itis possibleto Vary the characteristics of the power tube.

Referring to 1the .modification .shown in Figs.

2mand 4, the apparatus coinprisesan evacuated vesselvformed byhan 4outer metaltube 21 which acts as theanode and whichis closed atboth ends by means V,of glass members 22 .which are sealed to it and by means of ametallic tube 2?sealed` to the glass members.

" L As in au .the other modifications, me mami tube x 2 3 alone, may act asa control electrode, but,l

. Vcomprises a plurality of metaldiscs 24 mountedl when more effective control is desired, the grid is constructed in accordance with one of vthe modifications illustrated.Y The grid structure il- V lustratedis similar tothatshown in Fig. land on the metallic tube. 2 3 and heldin position by Washers 25 and collars-26. The lowerend of the menti-.ubc 2,3 is inademen, @passible bellQWSf like form, as indicated at 23a, in order to prevent the glass member'22 from cracking when lthe inner and outer tubes 23 and 21, respectively, expand unequal amounts. If desired, the tube 23 may be secured to the central reentrant portion of member 22 by means of a flexible disc, in the same waythat member 76 (Fig. 8) is secured to tube by means of the flexible disc 77.

The lament's 27 vare supported, at the lower end of the power tube, by means ci rods 27al of conductingmaterial. The rods 27a are secured to a metallic ring 28 which is bolted to rods sealed Ain, the reentrant glass portions 22a of the glass 'in the reentrant glass portions k22h of the upper glass member 22.. It will benoted that the rings 28a, and, consequently, the upper ends of the two filaments 27, shown in Fig. 2, are insulated from keach other.

As described in connection with Fig. l, each ring 28a preferably supports a plurality of laments, as indicated in Fig.' 4, Vinstead of only the one iilament shown in Fig. 2. Fig. 4 isa'view, in lat eralsection, of the structure shown in Fig. 2, with the exception that four additional laments are shown, i. e.,.two filaments have been added to each ring 28a..

When a grid structure is employed in which partof it is on the inside of the lament (as are the washers 25 .and central portion of dises 24), this part of thegrid will absorb some of the electrons when it becomes positive. This high grid.

current or absorption of electrons may be re-l duced considerably by employing the screening arrangement illustrated in'Figs. 2 and 4.

The screen comprises rods 29 which are at the same potential as the filaments 27 and which are positioned adjacent and parallel thereto. Each rod 29 is supported, at its lower end, by means of a metalsleeve 290., preferably made of some refractory material, welded or otherwise secured to the rod 2 9 and to the filament-supporting rod 27a.

VEach rod.29 is supported, at its upper end, by

means of a bushing 3 0 of insulating material, such as quartz mounted in one of the rings 28a. As shown in Figs. 2 and 4, each rod 29 is located between a filament 27 and the portion of the.

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grid on the inside of the filament referred to" above.

The anodesofthe power tubes constructed in accordance with the forms shown in Figs. 1 and 2 are cooled in .anysuitable manner.

. Referring to the modiiicaton shown in Figs.' 8 to 12,-' inclusive, the apparatus comprises an evacuated Vessel yformed by an outer metal tube 31 .which is closed at the upper end by being sealed to a glass niember32. VIt is closed at the lower end by means of a second glass member 33, which is sealed to it, and by means of a metallic reentrant portion 34 sealed tothe glass member 33 at a seal 35.

The reentrant portion 3 4. comprises a pipe36. closedat one end bya partition 37. i The pipe is extended for a short distance beyond the parti,- tion as a split portion 3 8 of reduced diameter.

yThe outer end of the pipeis enlarged to form a section 39 oi increased V diameter and the edges therefore reduced in thickness to form the seal- 35. A11-inner section 40 of .the enlarged section 39 isthreaded.

A .pipe 41. is'. held in screw-threaded]engagement with is@ ,ieiefef Sedi-9111.40 @ad Surgeries Lie.

fixed relation to the glass member 33 by means of a circular element 42 attached to the pipe 41. A pipe 43 of smaller diameter is positioned within, and spaced from, the pipe 41 andthe reentrant pipe 36 to provide means for cooling the grid as described in connection with the modica- .tion shown in Fig. 1 and also kto provide means for conducting heavy high frequency grid currents which may be generated when the tube is employed for short wave transmission.

In the modiiication illustrated inrFigs. 8 to l2, the controlv electrode is similar to that shown in Fig. 1 and comprises a plurality'of metal discs 44 mounted on the reentrant pipe 36 and held in position by washers 45 and collars 46. The structure may assume any of the modified forms previously described. -i y In order to prevent the upper endof the grid structure from swaying out of position and in order to provide means for supporting the laments 47, a rod 48 of quartz or other suitable insulating material is inserted into the split end portion 38. A metal cylinder 49 is sopositioned that it provides an'electrostatic rshield for lthe quartz rod 48 and prevents conducting deposits from forming thereon. The cylinder49 is split and held in position by means of a clamp 50 which also serves to clamp the quartz rod 48 in the split end portion 38.

The rod 48 extends into a hole drilled in the lower end of a metal rod 51. The upper .end of the rod 51 is attached to a piece 52 of sheet material which is so shaped that the rod 51 is firmly but slidably supported by the reentrant tube portions 53 of glass member 32.

In certain cases it is desirable to have ka connection leading from each end of the grid. For this reason, a conducting rod 49a is welded or votherwise suitably attached tothe cylinder 49 so that it extends through an insulating bushing a in the ring 55. The rod 49a is connected by means of a flexible conductor to a rod 49h sealed in the wall of the glass member 32.

A support of this character is required because the grid structure expands as the temperature of the power tube increases during operation. The lower end of the rod 51 is enlarged and provided with projecting portions 54 to which a ring member 55 is attached.

The upper end of each lament 47 is supported from the ring member 55 by means' of a structure comprising a rod 56 to the lower end of which the filament 47 is attached. VThe upper end of the rod 56 extends through a hollow supporting member 57 which is bolted to the ring 55; A spring 58 is mounted on the rod56 between a washer 59 attached to the rod .and the top of the supporting member 57 and is maintained in compression for keeping the individual laments 47 taut. f

The lower end of each filament 47 is attached to `a short supporting rod 60 bolted to a metal Aring 61. The ring 61 has a central hole therein of suiiicient diameter to prevent the ring from' coming into contact with the pipe 36.

The ring 61 is so supported that it holdsthe filaments 47 taut and keeps them insulated from the pipe 36 and the remaining grid structure.

The ringsupporting structure comprises four rods 62 of insulating material, preferably quartz. The ring is attached to each quartz rod by means of a strap which is bolted to the ring 61 and clamped to the rod 62. The other ends of the rods 62 are attached to another ring 64 by being clamped to split members 65 which are bolted to ing structure.

,riphery of -each annular supporting member 76.

the ring. The ring 64 is firmly supported' on the reentrant portion 34 and in slidable relation there-1- to by means of a plurality of rods 66 bolted to the ring'.` 'Ihe rods 66 are slidably supported in holes drilled in a ring 67 which is clamped tothe reen- -trantportion 34 by means of a collar'68.

A helical spring 69, usually made of tungsten, is supported on the reentrant portion 34between the ring 64 and a collar 70 which is secured to the reentrant portion by a set screw.- In this way, the spring 69 is held in compression to push the ring 64.toward the lower end of the tube and hold the iilaments 47 taut. A second collar 7lisl attached tothe reentrant portion 34 by means of a set screw to limit the movement of the ring 64 when attaching the filaments to their support- AAt the lower end, the filaments Y47 are electrically connectedlby means of the ring 61. At the kother end, the filaments 47 are connected to the G terminal rods 72 by means of binding posts 73 and lflexible conductorsl 85, oneflament beingr insulated from the ring 55 by means of a quartzbushling 57avand quartz washers 57h. While only two lamentshave beenshown for the sake of clearness, obviously more holes may be drilled in the discs 44, and any number of filaments desired (usually six or eight or more) mounted around the peripheries of the supporting rings 55 and 61'. In the latter modification, each alternate [05 filament is insulated from the ring 55.

One advantage of the tube structure described above is that the quartz rod 48, which formspart of the grid support, is prevented from melting.

A further advantage is that, by employing a cooled lin() grid and a glass member sealed to each end of the anode, the springs 69 and 58 are preventedvfrom becoming heated to such an extent that they lose their resiliency.

Obviously, the filamentsupporting structure i shown in Figs. 8, 9, and 1l may be (and preferably is) employed in the modied power tubes shown in the preceding figures.

The seals are Yprotected by means of metal shields 74 which are attached to the outer metal 120 wall 31. v

The anode-cooling structure comprises a vtube 75'which surrounds, and is spaced from, the anode 31. An annular supporting member 76 is vat tached, in liquid-tight relation, to eachend'of the (125 tube 75 by means of a ring-shaped flexible element 77. The exible element 77 prevents thebreakfv age of parts due to unequal expansion oftubes 31 and 75. Each 4annular supporting member` 76 vis mounted on the anode 31 and is held in liquid- 130 tight relationthereto by means of-ai gasket78 which is positioned over a threaded or groved portion of the anode 31. L 'f I In' order to form a liquid-tight joint, thev gasket 78 is compressed and forced into the'threaded 135 portions. This is accomplished by employing a f ring 79 held against each gasket 78 and in slidable relationto the anode `31,fanda plurality of levers 80 inthe form of hooks mounted around thepe- As shown in'Fig. 8, eachlever 80 is pivoted on 140 the head of a screw 81 so that the vhead of the screw forms the lfulcrum of the lever. The Ygaskets 78 are compressed as much as 'is convenient by turning the screws 81 thereby drawing vthe rings 79 against the gaskets. 'They'are' compressed the additional amount necessary for obtaining a liquid-tight joint by turning the screws A82 at `the ends of the levers 80 in such direction that Ythe funs ends of the shorter arms of the levers are pressed150 againsttherings 791to further compressV the gasket.

The cooling liquid is forced vinto the lower chamber 83 through an opening (not shown),

y`-`s5 -through the space between the anode 31 and the anode, a control-electrode comprising a`plurality Vmetallic tube and to said metallic member and `electrode means cooperating with saidl-metallic tube intoxthe. upper chamber 84, and out through vanother opening (not shown) Various modifications may be made in our invention without departing from the spirit and scope thereof, and we desire, therefore, that only such limitations shall begplaced thereonas `are shownby the prior art and set orthirrthe ap,- pended claims. g

We .claim as our-invention: l 1 A l. An electrendischarge device` having fan of discs mounted coaxially and spaced apart,-1each lof said discs having a plurality oiopenings Vadjacent toY the periphery thereof, and electron Yeni'itting elementsy extending through said openings, each of said discs comprisingportions encircling eachof said electron-emitting elements.

2. Anielectron-dischargev device comprising an evacuated vessel having a reentrant portion and having an outer wall which forms an anode, a

plurality 0f discs which form a control electrode supported Yby said reentrant portion, and cathode elements positioned between said reentrant portion and said anode and'extending through openings in said discs, each of said discs comprising portions encircling each ofsaid cathode elements.

3. An electron-discharge device comprising an outer metallic tube adapted to serve as Van electrede, a ,metallic tube closed at one end and yend of said outer metallic tube being sealed by positioned within said outer metallic tube, one

means of insulating material to the open end of said inner metallic tube, vnfieans including a member of insulating material for sealing the other endY of said outer metallic tube, and means in inner metallic tube having one end thereof closed f' and having the other end sealed to one end of said outer metallic tube, the other end of Ysaid outer metallic tube being sealed by meansof insulating material, a metallic member` supported byv said insulating material, and a member of insulating material secured to the closed end ofI saidinner tube when serving as an electrode.

'5.- Anr electron discharge device comprisingl an A,outer metallic tubel adapted to serve as an electrode, a metallic Vtube positioned therein, said inner metallic tube having one end thereof closed l and having the otherl end sealed to oneend of i said 'outer metallic tube, the other end o f saidl outer metallic tube being sealed by means of insulating material, a metallic member supported by said insulating material, a member of insulating material secured to the closed end of `said inner metallic tube and to: said metallic member, and a filament having one end thereofsupported by means of said lmetallic, member.

6; An electron discharge device comprising an outer tube, a metallic tube lpositioned therein, i

ze? f 'I said metallic tube having one end thereof closed and having theotherend sealed to one end of said outer tube, the other end of said outer tube being sealed by means of insulating material, a metallic member supported by said insulating material, a member lof insulating material secured to the closedendofsaid metallic tube and to said metallic member, and a lament having one end thereof supported by means of said metallic member and the'other end thereof supportedjby means of an element mounted on the openfend'of said metallic tube and insulated therefrom said fila- `tallic member and the other end thereoisupported by means of an element mounted on the open end of said metallic tubeand insulated there.- from, and means for giving said element a tendency toimove away from the closed end oi said metallic tube said lament cccperating with at least vone of said tubes to form an operative device.'` Y f y 8. Anlelectron-discharge device comprising an outer metallic tube, a metallic tube positioned within said outer tube, one end of said outer metallic tube being sealed by means of'insulating material to an end of said inner metallic tube, the other end of said outer metallic tube being closed by means vof'an insulating member sealed there- -to, a plurality of laments positioned longitudinally between said tubes and supported at one end by means of said insulating member, and'spring supporting means for said .filaments at each end of said outer metallic tube said lament's Vcooperating with at leasto-ne vof said tubes to form an Aoperative device. l r f 9. An electron-discharge device comprising an outer tube, a metallic tube positioned within said Vouteritube, one endof said outer tube being sealed bymeansof insulatingmateri'al to'an end Voi said metallic tubefthe other end of said outer tube being closedby means of an insulating memberl sealed'thereto, ar plurality of lfilaments positioned longitudinally between said tubes, and springsupporting means for each end of said i'llayments,- and means for holding said filaments taut, AAsaid means including a spring supported `by said vmetallic tube said Illaments cooperating with at least one of said tubes to form an operative device. 4lll. An Ielectrical discharge device comprising ia vacuum-tightenclosure', which has ametallic Wall portion adapted to constitute an anode', ia

metallic tubular member Yopen to the airvonat least one `end and encircled bythe iirst sai'dfmevtallic wall portion, a cathode within `said enclosure and'aplurality of lrnetal disk members suppcrted in good heat-conducting relation with 'said tubular membeiwand having aligned .openings through` which said cathode extends.'` f

' ILIA E. .MOUROMTSEFF. 

